Electrolytic apparatus



Nov. 17, 1931. K. TEUFEL ELECTROLYTIC APPARATUS Filed Feb. 11, 1928 Patented Nov. 17, 1931 UNITED STATES PATENT oFrIcE KONRAD TEUFEL, OF LEVERKUSEN-ON-THE-RHINE, GERMANY, ASSIGNOR TO I. G.

FARBENINDUSTRIE AKTIENGESELLSCHAFT, 0F FRANKFORT-ON-TI-IE-MAIN, GER- MANY, A CORPORATION OF GERMANY ELECTROLYTIC APPARATUS Application filed February 11, 1928, Serial No. 253,776, and in Germany February 21, 1927.

I The present invention concerns a process for safeguarding the uniform passage of electrolytes through electrolytic cells in the nuanufacture of metals by electrolysis and consists in arranging for the upward flow of the electrolyte, with respect to all electrodes, the electrolyte leaving both sides of the cells by means of overflows arranged for to be given to the circulation ofthe electrolyte. When the movement provided for the electrolyte is insufiicient, impoverishment of the electrolyte as to its metal contents, for example zinc, takes,plaee on those parts of the cathode which have thus suffered As a consequence of this the formation o flbuds or sponges as well as a development of hydrogen result, involving considerable disturbances in the electrolysis.

Ordinarily the electrolytejs introduced at one end of the electrolyticcell and leaves it at the opposite end. This arrangement, however, leaves the electrolyte to make its way at random through the bath the gas bubbles mainly risiiig from the anodes being supposed to promote the movement of the liquid. It is obvious that by such an arrangement a uniform movement of the electrolyte with respect to all the anodes cannot be produced during its passage through the cell. Consequently there was no lack of proposals for remedying this defect. First, for example, attempts were made to render the movement of the electrolyte uniform by blowing in air or by stirring with-rod shaped stirrers which were moved to and fro between the electrodes. According to anotherproposal intermediate passages were createdalternately between the lower end of the anode and the bottom of the vessel and the upper end of the adjacent cathode and the level of the liquid in such a manner that the electrolyte was forced to flow between the electrodes in an upward and downward direction.

These proposals, however, have never met with any appreciable technical success. In the first instance, this maybe due to inefiiciency of action. Further the complexity of the appliances involved in the employment of movable parts frequently promotes an excessive wear and tearof the apparatus, inasmuch as the gas bubbles rising out of the electrolyte and being laden with the acid lye are liable to settle on the joints and links of the movable. members and rapidly tend to corrode these parts.

Though the last mentioned proposal, providing intermediate passages enables a uniform movement of the electrolyte to be obtained at the lower and upper ends of the electrodes,'it still possesses considerable disadvantages. The application of intermediate passages imposes certain limits in regard to size and form of the anodes and cathodes as well as their respective disposition in the bath; the downward current of the lye is of particular disadvantage since it opposes the current of the rising gas bubbles moving in an upward direction whilst the flowing liquid and gas bubbles should of course mutually assist each other.

The present invention describes a process and an appropriate appliance forthe execution of the same whereby all requirements are satisfied. p

The process consists in introducing the electrolyte from below into the cells at one or more points, depending on the construction of the baths and withdrawing the electrolyte from the upper level of the bath by causing it to pass over weir-like overflows disposed in the upper part of the two opposite cell walls forming right angles with the plane of the electrodes.

For this purpose these overflows should be arranged at an equal level on both sides of the cell, the latter being advantageously provided with a bag for receiving the sludge. The lower part of the cell for this reason is preferably given a prismatic shape or the shape of a pyramid or cone, leaving sufiicient space, however, between the lower ends of the electrode or electrodes and the means for supplying the electrolyte.

.' The bottoms of the cells can like-wise consist of frustums of prisms or pyramids or cones or any one of these bottoms may consist of several similar prismatic or pyramid or c'one shaped elements. The bag for the sludge referred to may be constructed in such a manner that the tube or tubes introducing the electrolyte is or are extended somewhat beyond the bottom of the cell or a special bag may be provided as is shown in Figure 2 of the attached drawings.

It is important to leave sufiicient space between the lower end of the electrodes and the place at which the electrolyte is introduced so as to insure a uniform distribution of the liquid over the whole section of the cell before it reaches the electrodes. This distribution is promoted by the selection of a suitable angle of inclination of the planes of the prisms or pyramids or of the surface of the cone with respect to the horizontal plane.

The overflows can be constructed in such a manner that each overflow extends on each 'side across the entire length of the cell walls forming right angles with the plane of the electrodes. However, it is also possible to subdivide them into several overflows, for example in such a manner that an individual overflow is placed adjacent to the edge or rim of each individual cathode or anode. In any case, the construction must be effected in such a manner that each individual cathode surface is with certainty brought into contact along its whole extent with the stream of the electrolyte.

It is essential for ensuring a uniform flow of electrolyte to arrange all overflows at exactly the same level; this can easily be achieved by placing thin glass plates within the bath.

The Figures 1 to 6 of the attached drawings represent modes of constructing an appliance in accordance with my, invention which are directly understood based on the above description and without adding further details. v

Figures 1 and 2 are longitudinal sections, taken in a parallel direction to the electrodes, of two different embodiments of the invention. In these figures the side walls of the cell are represented by 1, while 2 denotes the bi-laterally tapered bottom of the cell acting as a sludge bag. 3 is a pipe for introducing the electrolyte into the cell which in Fig. 1 has an extension represented by 4 into the interior of the cell bottom, while in Fig. 2 a double bottom 8 is provided and pipe 3 enters the lower compartment of the cell somewhat above said bottom. 5 are the electrodes; 6 the weir-like overflows and 7 indicate outlets for the electrolyte after the latter has passed over 6.

Figures 3, 4 and 5 are ground plans of various shapes of bottoms 2; l designates the pipes for introducing the electrolyte.

Figure 3 represents a prismatic bottom Fig. 4'shows a bottom consisting of two and Fig. 5 a bottom consisting of a single pyram1 I Fig. 6 is a horizontal section through. a cell taken at the level of the overflows. In this figure the cathodes are representedby 5a and the anodes by 5b; the other numerals having the same significance as in the figures mentioned above.

Accordingly the new appliance neither possesses any movable parts that are subject to excessive wear and tear nor does it require permanent control. It enables a uniform flow of the electrolyte at all points of the electrodes and since the electrolyte flows over allthe electrodes only in an upward direction, the current of the electrolyte and the rising gas bubbles mutually assist each other. The gas bubbles increase the movement of the electrolyte and render the same completely uniform. The stream of the electrolyte directed upwardly facilitates on its part the removal of the gas bubbles from the electrodes.

This is of particular importance in respect to hydrogen bubbles forming on the cathodes, since if these hydrogen bubbles were to remain adherent to the cathodes inequalities of the deposited metal, for example zinc, would result leading to the formation of buds and sponges and finally to short circuiting cou-' pled with increased development of hydrogen.

I claim:

1. Apparatus for carrying out electrolytic processes of the kind described, comprising a trough of acid-proof material having vertical side walls and an at least bi-laterally tapered bottom part, a set of parallel vertical electrodes positioned within said trough but arranged so as not to extend into said bottom part, means for introducing a liquid'into the lower part of said bottom'part and at least two horizontally extending overflows at an equal level in the upper'part of the two opposite side walls of said trough perpendicular to the plane of the electrodes.

2. Apparatus for carrying out electrolytic processes of the kind described, comprising a trough of acid-proof material having vertical side walls and an at least bi-laterally tapered bottom part, a set of parallel vertical electrodes positioned within said trough but arranged so as not to extend into said bottom part, at least one supply pipe inserted in the proximity of the lowest point of said bottom part and extending into the interior of said bottom part, and at least two horizontally extending overflows at an equal level in the upper part of the two opposite side walls of said trough perpendicular to the plane of the electrodes.

In testimony whereof I have hereunto set my hand.

KONRAD TEUFEL. 

